1. Field of the Invention
The present invention relates generally to liquid crystal displays and, more particularly, to a liquid crystal display and touch screen technology for a windshield of an automotive vehicle.
2. Description of the Related Art
1) Liquid-Crystal
The technology of liquid-crystal is well known and extensively utilized. Calculators primarily use liquid-crystal for their numeric displays. These are known as liquid-crystal-displays (LCD). These LCD""s are produced in a variety of shapes.
Since liquid crystal molecules respond to an external applied voltage, liquid crystal can be used as an optical switch, or light valve. A common arrangement is two parallel glass plates, each with a polarizing film on its outer side. The space between the plates is filled with the liquid crystal polymer. The technical designation for the most commonly used liquid crystal type is twisted nematic (TN), and the twist refers to the tendency of the polymers to form chains that rotate from one side of the gap between the plates to the other side. This alignment can be changed with an external electric field, allowing the polarization of incoming light to be changed.
Light passing through one of the polarizers, then through the cell (the arrangement of plates, and liquid crystal), has its polarization direction rotated, following the physical rotation of the liquid crystal. When viewed, the cell is clear, or transmitting. A transparent electrical conductor is deposited on the inner surfaces of the glass plates, and patterned into a series of mutually perpendicular lines. If a voltage is placed across the cell gap by addressing the appropriate line on each side of the cell, the liquid crystal reorients to follow the applied electric filed, and the material is xe2x80x9cuntwistedxe2x80x9d. As long as the voltage is present, the passage of light will be blocked by the exit polarizer. When the voltage is turned off, the liquid crystal returns to its original state, and the pixel (defined viewing area) becomes clear again. Typical voltages and currents are quite low, which is why liquid crystal displays have been incorporated in battery-operated equipment, and in other applications where power consumption is an issue.
2) Heads-Up-Display (HUD)
Originally developed for the use of the military in fighter aircraft. Now HUD has been translated to broader commercial use in automotive vehicles.
A HUD works by reflecting an image off the windshield into the drivers line of sight. The image presented to the driver is information pertaining to the vehicle""s status such as speed. This allows the driver to easily determine the vehicle speed while looking out through the windshield. Thus allowing the driver to maintain their heads up position while driving instead of breaking their view of the road to determine speed. A light intensive image is necessary so that it is able to reflect off the windshield. The equipment necessary to generate the image is set below the windshield and the image generated is projected up into the windshield which in turn is reflected off the windshield and into the drivers line of vision. Sometimes special optics are used to define and focus the image so that after the image is reflected off the windshield the driver is presented with a clear and coherent image.
3) Touch Screen Technology
Touch screen technology is in use on many video screens to enhance user interface. The user can activate software selection simply by touching the display screen. One technical way of detecting if the display screen has been touched has been described in U.S. Pat. No. 3,636,409 by Norman J. Braaten. Transparent electrodes are placed on the surface of the screen. When a person touches one of the transparent electrodes, an increase in capacitance occurs which is sensed by the change in frequency of an oscillator circuit. The oscillations corresponding to the various electrodes are counted and compared to a threshold value to provide an indication of which, if any, of the electrodes has been touched. The software then uses this as input information and resumes with its program.
4) Dashboard Layout and Configuration
Due to the numerous amount of features currently available and with even more desired by designers the available dashboard real-estate is extremely limited. Also the available space is further constrained because some features are essential and required such as airbags. Among the features are things like; engine performance indices (engine temperature, oil pressure, electrical voltages, etc . . . ), air vents, vehicle speed, time, navigation aids, radios, CD players, cassette players, climate controls, cell phones, cup holders, etc . . . . All of these features are competing for very limited dashboard real-estate.
According to the present invention, an interactive heads up display (IHUD) is a passive information display and allowing selection that uses the windshield as the actual platform. Passive in the sense that the display isn""t generating the light, it simply locks ambient light. Activation of information on the IHUD is accomplished using the windshield as well. The interactive heads up display is the integration of the windshield, an LCD, and a selection device. So that the windshield acts as a multifunction device, as a device to shield the driver from wind, as a display platform and as a device to control the displayed information.
The interactive heads up display includes the following elements, two sheets of glass, a layer of liquid crystal, an annular shaped piece of plastic, three sets of transparent electrodes, two polarizing elements, and equipment to provide a voltage to the interactive heads up display assembly and to measure electrical characteristics.
The two sheets are congruent pieces of glass that when sandwiched together form the windshield. Sandwiched between these two sheets of glass is a very thin layer of liquid crystal. In addition, also sandwiched in between is a clear ring of plastic surrounding the liquid crystal to prevent the liquid crystal from moving so that its position remains static. Two sets of transparent electrodes are positioned at the inner surfaces of both sheets of glass so that electrodes are in direct contact on both sides of the liquid crystal. On the outside sheets of glass two polarizers, crossed with each other, are placed on both sides of the windshield over the region of the liquid crystal, so that any light passing through the liquid crystal will also first pass through one polarizer, the liquid crystal, and then the other polarizer. The windshield can now act as a LCD, except in a see-through mode. Whenever an electric field is applied to the liquid crystal via the transparent electrodes, this causes the region to appear dark. This by the principals of LCD. By arranging the electrodes in an ordered manner, any information can be displayed, such as can be noted by LCD presently found today. The third set of electrodes are attached to the surface of the windshield. This surface being on the interior of the vehicle and accessible to a vehicle driver/occupant. The vehicle driver/occupant can now easily touch these transparent electrodes and change the measured electrical characteristics of these electrodes. This change then be used to switch on or off the displayed information.
The interactive heads up display functions using the similar principals found on touch screen displays and on LCD calculators. Except the glass of the windshield acts as the implementation platform. First the glass acts as selection platform. And also the windshield acts as viewing platform as the case of a calculator. But the glass is not functioning exactly the same because the driver is presented the information by ambient light passing through the windshield.
The purposes of the present invention are as follows:
1. Currently because the space found on dashboards is limited and very valuable in terms of competing interests. The interactive heads up display would provide additional area for information display and selection. Allowing the designers a greater flexibility in designing the vehicle dashboard.
2. Currently the HUDs (heads up displays) used in auto vehicles implement a bulky system of reflectors and a CRT (cathode-ray-tube). The interactive heads up display would constitute a weight saving thus improving the gas mileage of the automotive vehicle. The weight increase would be minimal because the interactive heads up display would be using the windshield as the display platform which is already present on the vehicle. Thus providing an overall net weight savings.
3. The interactive heads up display would also constitute a space savings in place of the old type HUD system. Allowing the designers a greater flexibility in designing the vehicle dashboard by providing room for other instrumentation or increased interior dashboard room.
4. The interactive heads up display (IHUD) would use a minimal amount of current compared with the old type HUD system. Because LCDs (liquid crystal displays) require a minimal amount of current. Thus decreasing the power requirements supplied by the engine which would translate in a savings of fuel which would translate into increased gas milage. Also because of the reduced voltages there would be a corresponding reduction of EMI (Electro-magnetic interference) in the environment. This reduced EMI would improve radio reception due to the reduced noise in the received signal.
5. There is also increased awareness by the driver of the road because in order to make a selection the driver does not have to look away from the road. So fewer breaks of road observation are made.
6. Because the hardware for building an IHUD is less complex and extensive compared to a traditional HUD. Far more vehicles could be equipped with an IHUD, whereas now a HUD would not be considered due to prohibitive cost and weight. Any vehicle that has a windshield could be built with an IHUD as an option with very little redesigning. The electronics responsible for controlling the LCD would be comparable in cost with a hand-held calculator.
7. The cost of manufacture would also be reduced because the cost of attaching electrodes on the windshield would be cheaper than building a separate switch mechanism to control the IHUD.
8. The IHUD allows greater design flexibility than a traditional HUD. The IHUD can place information anywhere on the windshield that is desired. A traditional HUD is constrained by the placement of the equipment that reflects the information. No such constraints exist for the IHUD. In addition the IHUD can display information in two separate areas of the windshield at the same time. This is not possible with a traditional HUD. A traditional HUD can only display information in one particular region at one time.
9. The improved visibility in bright daylight. The IHUD would provide a very clear image in bright sunlight. In fact the brighter the day the better the image becomes due to the increased contrast. Unlike the traditional HUD, because the luminous image generated would be more difficult to ascertain against a background of bright or direct sunlight.